Lightning talk at the TypeScript NYC meetup: Babel 7 with TypeScript support

0-package.json

{
  "dependencies": {
    "@babel/cli": "^7.0.0-beta.34",
    "@babel/core": "^7.0.0-beta.34",
    "@babel/generator": "^7.0.0-beta.34",
    "@babel/node": "^7.0.0-beta.34",
    "@babel/preset-typescript": "^7.0.0-beta.34",
    "@babel/types": "^7.0.0-beta.34",
    "babylon": "^7.0.0-beta.34"
  }
}

1-wowzers.ts

/**
 * $ ./node_modules/.bin/babel-node --presets @babel/typescript --extensions .ts wozers.ts
 */

interface Wozers {
  foo: string;
}

const wow: Wozers = {
  foo: "bar"
}

console.log(wow)

2-babylon.js

/**
 * $ node babel-generator.js
 */

const { parse } = require("babylon")
const generate = require("@babel/generator").default
const util = require('util')

const source = `
interface Wozers {
  foo: string;
}

const wow: Wozers = {
  foo: "bar"
}
`

const ast = parse(source, { sourceType: "module", plugins: ["typescript"] })
console.log(util.inspect(ast.program.body, false, null))
// console.log(generate(x).code)

3-babel-generator.js

/**
 * $ node babel-generator.js
 */

const generate = require("@babel/generator").default
const t = require("@babel/types")

const properties = []
properties.push(t.TSPropertySignature(
  t.identifier("foo"),
  t.TSTypeAnnotation(t.TSStringKeyword()))
)
properties.push(t.TSPropertySignature(
  t.identifier("bar"),
  t.TSTypeAnnotation(t.TSBooleanKeyword()))
)
const objectLiteral = t.TSTypeLiteral(properties)

console.log(generate(objectLiteral).code)

const interfaceBody = t.TSInterfaceBody(objectLiteral.members)
const interface = t.TSInterfaceDeclaration(t.identifier("Wozers"), null, null, interfaceBody)
console.log(generate(interface).code)